Stir Fried Garlic Spinach with Mustard Seeds
I'm not quite sure how a nation that loves mustard as much as the U.S. pays so little attention to mustard seeds. We're pretty far out of the loop on this one: the French, the Chinese, the Indians—even the Brits consume the spice in great quantities. There's a lot more to mustard seed than a condiment in the making (though for that condiment, I charge you to find a better guide than this one). If you haven't explored what mustard seeds have to offer, it's an edible journey worth taking.
When they grow up, mustard seeds reveal themselves to be members of the cabbage family, producing dark, leafy greens like collards or kale. They're an ancient vegetable whose culinary cultivation dates back millennia as both food and medicine. Raw mustard seeds have a face-warping bitter quality that tastes like it'll scare any illnesses right out of you. That also made them just the thing for covering up the taste of rotting meat.
But when treated with heat, mustard's character changes completely. What was an awful, one-dimensional bitterness becomes a pleasant pungency that uplifts pickles, stir fries, curries, and all matters of roasted meat and vegetables. From appetizer to main course to, yes, condiment, mustard seeds are one of the most versatile spices you can have in your pantry.
Types of Mustard Seed
There are three types of mustard seed to look out for when shopping. The most common, Stateside anyway, is the plain jane mustard seed, pictured above. It's my favorite for pickles, meat rubs, and European and Western dishes like Boston Baked Beans. Yellow mustard seeds have a balanced, not-too-intense flavor, and their light color makes them easy to cook when heating them in hot oil (as their color darkens, you can pull them off the heat before they turn black and burn).
If you like your mustard with more kick, or have Indian cuisine set in your sights, brown/black mustard is the way to go. It's the same size as common yellow mustard seeds but with a more intense flavor that tastes more mustardy. Whole-seed deli mustards and dijon mustards use black seeds to get their piquant punch. I use these in all manners of curry, lentil soups, sautéed potato dishes, and roasted vegetables, especially when blended with other spices.
Less well-known, but worth having around are hot mustard seeds, also called "Chinese" or, if your merchant isn't feeling especially PC, "Oriental." Hot mustard seeds are much smaller than yellow or brown varieties, though they pack quite a wallop. To my taste, they're hotter but less interesting than brown mustard seeds. I like them for quick stir fries, especially with greens, where there aren't other spices to get in the way. While brown mustard seeds contribute complexity to spice blends, I think hot mustard seeds are best for adding zip to milder ingredients, like spinach.
How to Use Mustard Seed
Unless they're added to a pickle brine, mustard seeds need to fry and pop in hot oil to release their full potential. In quick stir fries, toss them in oil with finely minced aromatics like ginger and garlic. Just make sure your oil is hot when the seeds go in—if they heat up with the oil, they're likely to overcook and burn without popping. When the seeds start popping, I put on a lid till they down, then add more ingredients to cool down the pan. Don't keep the lid on too long though, as mustard seeds can burn quickly. If this happens to you, don't sweat it, but you may want to clean out your pan and start again. Burnt mustard seeds taste a little like motor oil.
With Indian curry-style dishes, I enjoy mustard seeds in concert with cumin, asafoetida, coriander, fennel, and curry leaf (though not all necessarily at once). You can fry these spices together before adding wet ingredients. Or, if making a lentil dish like daal, you can use mustard seeds as the foundation for a quick tarka. When the soup is just done, fry mustard seeds and some other spices in some hot oil, then spoon the mixture over the soup in bowls. It's like a finishing drizzle of extra virgin olive oil or a fresh pat of soft butter, but pungent and spicy. Don't limit this technique to Indian dishes, though: it's the best soup trick I know, hands-down.
Where to Find Mustard Seeds
Mustard seeds, even brown ones, are decently common in grocery stores, so you shouldn't have to look too far. But for freshness, price, and sheer volume, Indian groceries are your best bet. A couple of bucks will get you a year's supply of yellow or brown seeds. Hot mustard seeds are trickier to find, but you can get them online at The Spice House, three ounces for $3.
Start cooking with mustard seed with this recipe for Stir Fried Garlic Spinach with Mustard Seeds »